How to configure thresholds visualisation by JSON or other ways?

Grafana 7.4.0 release.
I use “between” alert, but I want hide one of the two thresholds line.
Edit JSON don’t work.
I try edit some source by this example but restart grafana and nginx don’t bring result. I think I do something wrong with apply changes.

  1. How to apply change if I change .ts scripts or .html files?
  2. Does exist simple way to modify alerts threshold line/fill/color view?